The present invention relates to natural stone veneer products, and more particularly to a method and apparatus for making the same.
Stone veneer products made from naturally occurring stone materials such as limestone, marble, granite and the like, have long been used in the construction industry for decorative purposes because of their inherent beauty. However, natural stone veneer products are difficult to make and are expensive due to high production losses as a result of breakage and high handling costs.
Because stone veneer products are typically applied to inside and/or outside wall surfaces, the weight of the stone product is a major concern. Typically, individual limestone veneer products weigh about 15 pounds per square foot. Therefore, it would be desirable to provide a lighter stone veneer product which is of a weight that can be easily handled without breaking. Also, it is desirable to provide as little thickness of stone material as possible so as to reduce costs and extend the supply of natural stone material.
It is therefore an object of the present invention to provide an improved method and apparatus for manufacturing stone veneer products.
It is a further object of the present invention to provide such a method and apparatus which permits manufacturing stone veneer products that are relatively thin so that the weight of each veneer product can be reduced.
It is yet another object of the present invention to provide such a method and apparatus which is faster, more efficient, less expensive, higher in yield and less wasteful than prior production methods.
In order to accomplish the above objects, the present invention provides a method of cutting a natural stone to make a stone veneer product. The method includes the steps of conveying a stone to be cut at a desired speed along a cutting path, and cutting through the stone to form a pair of stone veneer products. The step of cutting through the stone comprises making a plurality of sequential cuts in the stone with each subsequent cut being deeper than the previous cut as the stone moves downstream along the cutting path until the stone is cut completely through to form the pair of stone veneer products. Preferably, the stone is cut completely through in three steps, i.e. cutting to a first depth which is approximately one-third through the stone, thereafter cutting to a second depth which is approximately two-thirds through the stone, and finally cutting to a third depth which is completely through the stone. In one particularly preferred embodiment, the method includes the additional step of controlling the desired speed of the stone as it moves downstream along the cutting path as a function of resistance of the stone to cutting. Controlling the speed of the stone is accomplished by sensing the resistance of the stone to cutting, comparing the sensed resistance to a predetermined resistance value, and reducing the speed of the stone along the cutting path if the resistance to cutting exceeds the predetermined value.
It is also desirable to provide an apparatus for cutting the stone to make a pair of stone veneer products. The apparatus includes a conveyor for conveying a stone to be cut at a desired speed along a cutting path, a clamp for clamping the stone in a desired position on the conveyor, and a plurality of aligned saws for cutting through the stone to form a pair of stone veneer products. The saws are positioned to make a plurality of sequential cuts in the stone with each subsequent cut being deeper than the previous cut as the stone moves downstream until the stone is cut completely through. Preferably, a first saw cuts approximately one-third through the stone, a second saw cuts approximately two-thirds through the stone and a third saw cuts completely through the stone.
The apparatus preferable further includes control means for controlling the desired speed of the stone as a function of resistance of the stone to being cut. The control means includes sensing means for sensing the resistance of the stone to being cut, comparator means for comparing the sensed resistance to a predetermined resistance value, and speed reduction means for reducing the speed of the stone along the cutting path if the resistance to cutting exceeds the predetermined value. Preferably, each saw is driven by an electric motor and the sensing means senses amperage of at least one of the electric motors. If the amperage sensed exceeds a predetermined value, the control means slows the conveyor so that the saws more efficiency cut through the stone.
In a particularly preferred embodiment, the apparatus includes a trolley on the conveyor for receiving an individual stone workpiece, and a clamp which includes a pair of jaws integral with the trolley. One of the jaws is preferably stationary and thus functions as a reference datum for properly locating the stone to be cut with respect to the saws. The other jaw is preferably moved in a direction which is transverse to the cutting path to hold the natural stone workpiece in the proper position. The means for moving this jaw preferably comprises a screw member and a ball joint interconnecting the screw member and the jaw. Each jaw also preferably includes a clamping face, such as a rubber lining, which is adapted to substantially conform to the textured surface of the stone workpiece. In this manner, the stone workpiece can be securely clamped in the proper position for being cut by the saws.